1. Field of the Invention
The present invention relates generally to an image forming apparatus, and more particularly to an improved rake mechanism for a waste toner collection system in an image forming apparatus.
2. Description of the Related Art
Image forming apparatus, such as electrophotographic (EP) printers or copiers, typically use particulate developer material (toner) in the imaging operations. Such machines form output images by depositing toner onto a charged roller or other photosensitive member according to a latent print image and then running that toner to a media sheet.
Some amount of residual toner remains on the photosensitive member after image transfer and requires removal, such as by bringing a cleaning blade or other scraping mechanism into contact with the photosensitive member. The waste toner thus removed may be collected within a container included in the image forming apparatus. Potentially significant amounts of waste toner may be collected over time, particularly in machines that include multiple process cartridges, each of which acts as a source of waste toner.
In U.S. Pat. No. 7,280,776 to Cook et al, an image forming apparatus is described that includes a waste toner system that collects waste toner in a waste toner container. An amount of waste toner collected in the container is increased by using a driven toner distributing member (rake) that distributes accumulated toner within the container. The waste toner system may detect the accumulation of waste toner by monitoring a drive control circuit while the toner distributing member is being driven. For example, the system may detect excess accumulation by comparing the monitored values of a frequency control signal with one or more reference values corresponding to nominal accumulation conditions. An extension may be employed whereby movement of the toner distributing member creates interference between the toner distributing member and the container when the toner distributing member reaches a predetermined position. The interference may be detectable from the drive control circuit as an indication of a full condition. The entire contents and teachings of the Cook et al patent are incorporated by reference herein.